Actually it is better to use a gloss clear coat (like future) to protect your base coat. A gloss clear coat is smoother and thus more slippery. This will enable you to remove the excess wash quite easily. It will alo facilitate good decal setting.
Usually, you can brush a thin coat of the wash all over the model but you need to remove the excess wash before it dries up. This will leave only the recessessed portions with a darker/dirtier color.
You can simulate worn our surfaces by drybrushing the raised details and protruding corners with a color lighter than the base coat.
Once you are finished with the weathering process, you can seal your work with a dull or matt clear coat to remove the unwanted shine.
As far as I know those are the basic procedure and it might be helpful if you can go with them.
On the other hand I as far as what I am doing...
I don't apply a clear coat to protect my base coat. (I only do that for A/C...oops
![Tongue [:P]](/FSM/CS/emoticons/icon_smile_tongue.gif)
.)
I don't remove excess wash rather let them flow to the recesses and corners.
I rarely drybrush.
And I rarely use dull coats (only when necessary to knock off stubborn shines.)
But please consider that I build not for competition so procedural matters such as the above are not so important to me at this time. I am still trying things out.
For more info please try to do a search in the forum.
Good luck.